1. Field of the Invention
The present invention relates generally to supersonic gas flow devices, and more specifically to short length, low weight and volume supersonic diffusers suitable for converting low-pressure supersonic gaseous flows to high-pressure subsonic gaseous flows in such devices.
2. Description of the Prior Art
In mobile chemical laser systems, the gas providing optical amplification is usually flowing at a supersonic velocity. Supersonic diffusers are used to convert the low-pressure and high-velocity gaseous flow (supersonic flow) to a high-pressure and low-velocity gaseous flow (subsonic flow). The primary function of the diffuser is to decelerate the gaseous flow from a maximum velocity to a much lower velocity, and to recover as much as possible of the flow's original kinetic energy in the form of increased pressure. The flow mechanism most typically relied upon is the normal shock structure that requires a duct length on the order of 10 duct heights to facilitate a gradual flow deceleration and associated pressure increase without causing large energy losses and flow unsteadiness. Generally, the normal shock is generated when the supersonic flow existing outside a diffuser wall boundary layer, shocks the downstream flow from supersonic to subsonic. Because the boundary layers cannot withstand the attendant large pressure rise which causes them to separate from the diffuser wall, an effective expanding flow channel having a supersonic core flow region results.
Because mobile gas laser systems must be transportable, diffuser designs for such systems must have the shortest length, and lowest weight and volume possible without compromising the diffuser's pressure recovery abilities.
What is needed therefore is a system that includes a compact supersonic diffuser having increased pressure recovery capabilities and reduced length, weight, and volume.